Cup grease



Patented Jan. 29, 1935 CUP GREASE William P. Hilliker, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application August 9, 1932,

Serial No. 628,111

'lClaims.

This invention relates to lubricants and it pertains more particularly to. that type of a lubricant which is generally referred to as cup grease.

Cup greases as a class have one drawback i which materially limits their applicability and utility. This one material drawback is their lack of stability at high temperatures. If cup greases are used at temperatures of 170-200" F. their structure breaks down and the hard soap separates out, frequently causing feed pipes to become clogged, and/or causingthe seizure of bearings or the restriction of free rolling motion of balls or rollers.

The object of my invention is to provide a cup grease which will not decompose or separate at these elevated temperatures, particularly in the range of from 170-220 F. A further object is to provide a cup grease which, when it does separate, yields a soft soap instead of .a hard soap, thereby insuring continued lubrication and preventing seizure of bearings. A further object is to provide a lubricant which can be used where present cup greases are inoperative, particularly in hot dispensing systems in the steel industry and in the lubrication of ball bearings. A further object is to provide an improved method of making greases, to obtain greater uniformity, to decrease the costs, etc.

In practicing my invention I depart from conventional practice in two important respects. First, I use a diflerenttype of calcium soap, one which is more uniform and which yields a remarkably superior product; second, I modify the process of making the lubricant by using a dif- 35 ferent order of steps, higher temperatures, and

extended period of stirring, etc. The invention will be more clearly understood from the following detailed description of a preferred embodiment.

In practicing my invention I may use the followingformulas: ingredients to make a 100 pound batch of finished cup grease from acid (1) or gluceride (2) P Pounds Pounds cid 14. 00 Glycer 14. 70 Hydrated lime 1. 80 1. 80 Caustic soda 0. 0. 20 am 1. 80 2. 70 Petroleum oil. 83. 70 82. 05

Analysis Percent Percent Calcium soap 15. 00- 15. 00 Water 1 1. l. 30 Glymr Trace l. 65 P 83. 70 82. 05

The acid and glycerides referred to in this forfats usually employed in the manufacture of cup greases. The glycerides are hydrogenated products obtained by hydrogenating vegetable or animal oils. Fish oils, cottonseed oils, rapeseed oil, corn oil, whale oil, etc. may behydrogenated individually or in admixture with other oils. I prefer to hydrogenate oils which will yield acids largely of 18 carbon atoms, and these hydrogenated oils are usually made from Menhadin oil containing appreciable amounts of cottonseed and/or rapeseed oil. The particular process for hydrogenating the oils and splitting the acids therefrom forms no part of the present invention and will therefore not be described in detail. The hydrogenated glyceride and the acid split therefrom may be distinguished from natural fats and fatty acids by the relation between their physical and chemical constants such as the titre, iodine number, percent acid, and neutralization value. These acids are of the fatty acid type, they are saturated, they contain from- Cu to C22 chains (structural formula) and their C15 content is less than 15%. I have found, however, that hydrogenated products with specifications closely resembling natural products in these respects show a markedly different behavior in cup greases. 1

In the following specification and claims,my improved glycerides will be called hydrogenated fatty oils or hydrogenated fats, and the acids split therefrom will be called hydrogenated fatty acid (even though the acid is split. from the hydrogenated oil and is not hydrogenated as an acid).

Heretofore cup greases have been prepared by mixing water, oil equivalent in quantity to the fatty acid to be used, and lime, in a steamjacketed grease mixer. The fatty acid is then added and heat is applied. After an'interval of about 40to 60 minutes, when. the temperature has reached 240260 F., the soap is ready for mixing. About 2% to 3% of water is added, and when the batch foams up it is driven down by the addition of oil, the heat being abstracted by the addition of cold oil and by the vaporization of water sothat the temperature drops to about 230 F. Oil is added until the batch contains about 25% soap, and during this interval the temperature drops gradually until its reaches about 205-210 F. If the desired soap percentage is about 15, the batch should reach a tempera ture of about 180-190 F. at this point. This process is about the same for, fats as for fatty acids except that it requires 12 to 20 hours at 240-260 F. to effect the saponiflcation of the fats.

Numerous attempts have been made to manufacture calcium soap greases from commercial stearic acid, oleostearin, etc.,--the acids of which have a titre above 48 F., but attempts along this line have been unsuccessful. When hydro- 00 mulaare very different from the fatty acids and genated fats and acids of equivalent titre test are employed I have found that much more satisfactory results are obtained. However, the most satisfactory results are accomplished by the use of the following preferred process.

An amount of oil equal to the amount of fatty acid used is admixed with lime and water in a steam-jacketed mixer, and the hydrogenated fatty acid is mixed therein and heated to about 260 F. Instead of limiting the temperature to 260 F., however, I raise the temperature to about 1300 F. and I maintain the heating step for a longer interval, usually from an hour to an hour and a half. The batch is then cooled to approximately 240 F., and 1% of water, based on the finished batch, is added. Oil is worked in and the/temperature is permitted to drop gradually until at a point of 33% soap a temperature of about 220 F. is reached. The balance of the oil is added while the batch is maintained at a temperature of about 220 F. or slightly above, and during this addition of oil small additions of water, usually about .2%. are added from time to time, depending on the condition of the batch. If a pressure kettle is used, the addition of water is not essential, but the mixture should be regulated so that there is always about 1% water on the finished batch.

After all of the oil has been added and the temperature is still up to 220 F., the stirring is continued but the heat turned off-the batch being allowed to drop to a temperature of l-210 F. If the batch is filled out and run into containers at this point, the finished greasev will have a consistency higher than the normal consistency for the given soap content but will, on aging, drop in consistency. I prefer to avoid this consistency drop and to maintain a uniform consistency, and I find that this can be accomplished by stirring the batch at 190-210 F. for another hour or hour and a half. The finished grease then has a consistency which is stable against aging.

The temperature during the final grading may be higher than 220 F. without separation, but more frequent additions of water are required at these high temperatures.

It should be understood, of course, that the preferred process hereinabove described is adapted only for use of hydrogenated fats or hydrogenated fatty acids, because if this material is used for naturally occurring fats or fatty acids, such as tallow, lard oil, etc., the batch will separate out into soap and oil at these high temperatures.

I have made many attempts to prepare cup grease from stearic acid, but in no case have I obtained a grease structure which was stable at these high temperatures. The stearic acid mixtures always break down and give a mixture of hard, soap-oil lumps in oil,a mixture resembling oil-soaked sawdust. Furthermore, ordinary stearic acid having a titre of about 50 could not even be used in the old process which I referred to above (before describing my improved process). In all cases, the soap will separate and all of the grease makers tricks'to catch these batches by the addition of small amounts of fatty acid, etc. are in vain. I am unable to explain why the hydrogenated fats and fatty oils are so radically different from naturally occurring fats and oils in the art of grease making, but the fact remains that this difference is that between success and failure.

Ordinarily cup greases range from about 4% to 35% of soap, and the oil,viscosity varies from about 80 seconds Saybolt at F. to 200 seconds Saybolt at 210 F.the lower soap-content greases separating at lower temperatures. I I have found that greases prepared from hydrogenated fats not only withstand high temperatures, but when they are subjected to extremely high temperatures, such as 260-270 F., and they do separate, the separation is slow and a soap is obtained which is much softer than that which separates from a regular cup grease. This soapin-oil is really a soap-oil aggregate which separates from the balance of the oil. Apparently in the case of hydrogenated fat greases this aggregate contains a much higher percentage of oil than is usually the case. This is extremely important in actual use, because if a bearing momentarily is heated to a high temperature and.

hard soap separates out, friction is materially increased which will, in turn, raise the temperature still further, and a complete failure of the grease and bearings results. On the other hand, when the only effect is the separation of a small amount of soft soap, the friction is not materially increased and the bearing recovers as the load is removed. Another feature of my hydrogenated fat or fatty acid cup greases is the fact that the consistency of the grease is greater for a given soap content than when ordinary fats and acids are employed. It should be understood that mica, graphite or other materials may be added to the grease without departing from this invention.

It will be understood that the invention is concerned primarily with calcium soap greases, that if hydrogenated fats are used instead of acids, a longer period of time will be required to make the soap base, that greases of high soap content may be filled at higher temperatures than greases of low soap contents, etc.

While I have described in detail a preferred example of my invention it should be understood that I do not limit myself to the details therein set forth except as defined by the following claims, which should be construed as broadly as the prior art will permit. a

I claim: 4

1. The method of making cup grease which comprises heating a small amount of oil, water and lime with a hydrogenated fatty compound at a temperature of about 260-300 F., for about an hour, cooling the batch to about 240 F., adding small amounts of water with the residual oil until a temperature of about 220 F. is reached, maintaining the temperature at about 220 F. during the addition of the remaining oil, and stirring the finished grease at a temperature of about 210 F. for about an hour so that the consistency of the grease will not fall off on aging.

2. The method of making a cup grease which will be stable at temperatures of PTO-200 R, which comprises processing oil with a small amount of water and with about 2 to 35% of a calcium soap of a hydrogenated fatty compound by first heating the calcium soap with a small amount of the oilto a temperature of about 260-300" F. and then working in the rest of the oil at a temperature upwards of about 220 F.

3. A cup grease of the class described which comprises about the following formula:

Calcium hydrogenated fatty soap 2to 35% Water About 0.3 to 1.5% Glycerine Trace to 4% Petroleum oil Balance to 100% 4. The method of making a cup grease of improved temperature stability, which comprises heating a small amount of petroleum oil, water and lime with a hydrogenated fatty compound at a temperature of about 260-300 F. until saponification is essentially completed, working in oil and small amounts of water until a soap content of about 2% to is reached, while gradually lowering the temperature of the batch to about 220 F.-, the amount of water being sufficient to leave about .3% to 1.5% in the finished product, and stirring the batch at a temperature of about 10-30 below the final processing temperature to stabilize the grease against aging.

5. The method of making a cup grease of improved high temperature stability, which comprises processing oil and a small amount of water with about 2% to 35% of a lime soap of a hydrogenated fatty compound having a titre of about 48 F., the oil and limesoap of hydrogenated fatty compound being processed at a temperature above the boiling point of water until all of the oil has been worked in.

6. The method of making a cup grease of im-' proved high temperature stability, which comprises heating substantially equal parts of oil and a hydrogenated fatty acid having a. titre of about 48 F. with lime and water at a temperature of about 260-300 E, maintaining said temperature for about an hour to an hour and a half, cooling the mixture to about 240 F. adding about 1% 'of water based on the finished batch, working in the oil and gradually lowering the temperature until, at a point of about 33% soap, the temperature of about 220 F. is reached, work-. ing-in' the rest of the oil at a temperature of about 2201K, adding small amounts of water so that thejfinished product will'contain about 1% water'iand about -97" oil, and finally stirring the mixture at a temperature below the final processing temperature for "stabilizing the grease against aging.

'7. An improved cup grease stable for extended periods at a temperature in excess of F. characterized in that it is prepared from the lime soap of a hydrogenated fatty compound, the acids of which have a titre of about 48 F., said cup grease having about the following formula:

Calcium hydrogenated fatty soap 2 to 35% WILLIAMRHILLIKER. 

